1. Technical Field
The present invention relates to a display device capable of driving a plurality of display panels having different panel characteristics one another.
2. Related Art
In the past, there was known an active matrix display device which supplies a predetermined precharge signal to signal lines immediately before an image signal is written to pixels arranged in one row (for example, see JP-A-H07-295521). This active matrix display device supplies a precharge signal having a middle level of the image signal which varies between a white level and a black level.
Moreover, as a display device performing polarity reversion driving in each of lines, there is known a display device in which a positive precharge signal in positive voltage driving and a negative precharge signal in negative voltage driving are asymmetric with respect to the center of the amplitude of an image data voltage (for example, see JP-2003-202847).
There is also known a display device such as a digital video camera or a digital still camera which includes two display panels and simultaneously drive the two display panels by use of one chip IC as a control circuit (for example, see JP-A-2006-154225). In such a display device, when the two display panels are mutually displayed, the display panel which does not perform a display just performs precharge driving to supply a precharge voltage to pixels.
However, the display panels have different panel characteristics such as a driving frequency and a driving voltage in accordance with a driving method, a panel size, or the like. When the display panels having the different panel characteristics are simultaneously driven by use of the one chip IC, appropriate precharge voltages are different from each other and a voltage (for example, a central voltage of the amplitude of the image data voltage in the display panel which performs the display) set in correspondence with the panel characteristics of the display panel which performs the display is set as the precharge voltage in the precharge driving in a general way.
In this case, however, in the display panel (which is the display panel just performing the precharge driving) which does not perform the display, a different pixel voltage is written to each frame. Therefore, since a DC voltage is normally applied, a problem with burn-in may occur.
The panel characteristics of the display panel are different depending on a method of driving a liquid crystal display panel. As the method of driving the liquid crystal display panel, there are known two methods, that is, a longitudinal electric field driving method of driving liquid crystal molecules by use of an electric field (a longitudinal electric field) generated between pixel electrodes of one glass substrate and a common electrode of the other glass substrate and a transverse electric field driving method of driving liquid crystal molecules by use of an electric field (a transverse electric field) generated in an in-plane direction with respect to a glass substrate. In general, it is known that the burn-in occurs more easily in the transverse electric field driving method than in the longitudinal electric field driving method. Accordingly, when the display panel which does not perform the display is a liquid crystal display panel employing the transverse electric field driving method, the burn-in is easily caused due to application of the DC voltage.